Abstract: The purpose of this research is to understand the pollution degree, ecological risk and spatial distribution characteristics of heavy metals in the soil of Qilian Mountain National Park. The content of V, Cr, Mn, Ni, Cu, Zn, Cd, Pb, As, and Hg in 0-10 cm and 10-20 cm of swamp meadow soils in the southern piedmont of Qilian Mountains were tested. The pollution coefficient and enrichment coefficient were used to study the enrichment rules and pollution characteristics of heavy metals in different parts. The human contribution rate was used to supplement and verify the results. Finally, the risk status was quantitatively assessed through the potential ecological risk index. Results showed that: 1) The average content of Cr, Zn, and Hg in the 0-10 cm and 10-20 cm swamp meadow soils are higher than the background value of Qinghai Lake soil. Cr and Zn are slightly enriched while Hg is the most obviously enriched with the human contribution rate reaching 30%. 2) The average content of V, Mn, Ni, Cu, Cd, Pb, and As shows no difference with the natural values. The human contribution rate is negative and shows an increasing trend as depth increases. It is worthy of attention that point source pollution exists at some sampling points. 3) The potential ecological risk value of heavy metals in descending order is Hg>Cd>As>Ni>Cu>Pb>Cr>V>Zn>Mn. Except for Hg, the other nine heavy metals are all at a status of level-I ecological pollution risk, which means slightly polluted. 4) The comprehensive potential ecological risk index (RI) of heavy metals in swamp meadow soil reached level-II medium ecological pollution in both 0-10 cm and 10-20 cm. The contribution rate of Hg to RI reached more than 50%. In general, heavy metal pollution in swamp meadow soil poses potential risk. Sufficient attention should be paid to the pollution control of swamp wetland. This research can provide basic data for the governance and improvement of ecosystem in the hinterland of the southern foothills of the Qilian Mountains.

Key words: swamp meadow soil, heavy metals, pollution evaluation, potential ecological risk, southern piedmont of Qilian Mountains